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United States Patent |
5,592,942
|
Webler
,   et al.
|
January 14, 1997
|
Automated longitudinal position translator for ultrasonic imaging
probes, and methods of using same
Abstract
A longitudinal position translator includes a probe drive module and a
linear translation module. The probe drive module is coupled operatively
to an ultrasonic imaging probe assembly having a distally located
ultrasound transducer subassembly in such a manner that longitudinal
shifting of the transducer subassembly may be effected. The probe drive
module is preferably mounted to the linear translation unit so as to be
moveable between a condition whereby longitudinal shifting of the
transducer subassembly can be conducted either manually or automatically.
When in the automatically-operable condition, the probe drive module will
be engaged with a motor-driven screw associated with the linear
translation module so as to cause the probe drive module to be
longitudinally displaced at a constant motor-driven rate. In this manner,
the distally located ultrasound transducer is longitudinally shifted
during an ultrasound scan of surrounding intravascular (or other) tissue
to thereby allow axially-spaced 360.degree. data sample "slices" of the
surrounding tissue to be obtained. The data samples may then be
reconstructed into a three-dimensional or other two-dimensional
representations of the scanned vessel to assist in diagnosis.
Inventors:
|
Webler; William E. (Costa Mesa, CA);
Buhr; Mark S. (Newport Beach, CA)
|
Assignee:
|
Cardiovascular Imaging Systems, Inc. (Sunnyvale, CA)
|
Appl. No.:
|
573507 |
Filed:
|
December 12, 1995 |
Current U.S. Class: |
600/445; 600/446; 600/463 |
Intern'l Class: |
A61B 008/00; A61B 008/12 |
Field of Search: |
128/662.06,660.03,660.1,660.09,916
73/623
|
References Cited
U.S. Patent Documents
4679551 | Jul., 1987 | Anthony | 128/67.
|
4708125 | Nov., 1987 | Miketi et al. | 128/4.
|
4753248 | Jun., 1988 | Engler et al. | 128/736.
|
4771774 | Sep., 1988 | Simpson et al. | 128/305.
|
4794931 | Jan., 1989 | Yock | 128/660.
|
4802487 | Feb., 1989 | Martin et al. | 128/662.
|
4815661 | Mar., 1989 | Anthony | 239/102.
|
4951667 | Aug., 1990 | Crowley | 128/662.
|
5000185 | Mar., 1991 | Yock | 128/662.
|
5105819 | Apr., 1992 | Wollschlager et al. | 128/662.
|
5107844 | Apr., 1992 | Kami et al. | 128/662.
|
5115814 | May., 1992 | Griffith et al. | 128/662.
|
5125410 | Jun., 1992 | Misono et al. | 128/662.
|
5178148 | Jan., 1993 | Lacoste et al. | 128/662.
|
5211176 | May., 1993 | Ishiguro et al. | 128/662.
|
5255681 | Oct., 1993 | Ishimura et al. | 128/662.
|
5295486 | Mar., 1994 | Wollschlager et al. | 128/661.
|
5361768 | Nov., 1994 | Webler et al. | 128/660.
|
5421338 | Jun., 1995 | Crowley et al. | 128/660.
|
Foreign Patent Documents |
0212225 | Jul., 1986 | EP.
| |
WO90/02520 | Mar., 1990 | WO.
| |
WO90/13259 | Nov., 1990 | WO.
| |
WO92/03095 | Mar., 1992 | WO.
| |
Primary Examiner: Jaworski; Francis
Attorney, Agent or Firm: Lyon & Lyon
Parent Case Text
This application is a continuation of U.S. application Ser. No. 08/285,969,
filed on Aug. 4, 1994 and now U.S. Pat. No. 5,485,846, which is a
continuation of U.S. application Ser. No. 07/906,311, filed Jun. 30, 1992,
now U.S. Pat. No. 5,361,768. All of the above-identified patents and
applications are expressly incorporated herein by reference.
Claims
What is claimed is:
1. An automated longitudinal position translator for ultrasonic imaging
probes having a housing and a distally located ultrasound transducer
subassembly, said position translator comprising:
a probe drive module which rotates the ultrasound transducer subassembly of
the imaging probe;
a motor-driven linear translation module to affect motor-driven
longitudinal translation of said probe drive module to longitudinally
shift said ultrasound transducer subassembly between spaced-apart
positions relative to said probe housing; and
means for coupling said probe drive module to said translation module to
allow for switching between an automatically-operable condition wherein
said probe drive module is coupled to said motor-driven translation module
to affect said motor-driven longitudinal translation thereof relative to
the probe housing, and a manually-operable condition wherein said probe
drive module is capable of being longitudinally shifted manually relative
to the probe housing.
2. The position translator of claim 1, further comprising at least one
elongate guide rail.
3. The position translator of claim 2, further comprising a second elongate
guide rail, such that the position translator has a pair of elongate guide
rails.
4. The position translator of claim 3, further comprising forward and
rearward transverse support arms connected to and spanning the distance
between said pair of elongate guide rails.
5. The position translator of claim 4, wherein said linear translation
module includes a pair of restraining posts adapted to contact respective
ones of said forward and rearward transverse support arms in interference
fit so as to releasably restrain said probe drive module in said
automatically-operable condition.
6. The position translator of claim 1, wherein said ultrasound transducer
subassembly of said ultrasonic imaging probe includes a flexible rotatable
drive element disposed within a flexible guide catheter sheath.
7. The position translator of claim 6, further comprising:
a longitudinally fixed but rotatable drive coupling capable of being
fixedly attached to the proximal end of said rotatable drive element; and
a longitudinally adjustable coupling which is longitudinally adjustable
with respect to said rotatable drive coupling and which is capable of
being fixedly attached to the proximal end of said guide catheter sheath.
8. The position translator of claim 7, wherein said longitudinally
adjustable coupling includes a barrel-shaped housing having a
longitudinally extending slot.
9. The position translator of claim 8, wherein said housing includes upper
and lower housing sections, and wherein said lower housing section defines
an inner bearing surface for supporting said positioning arm during
movements thereof between advanced and retracted positions.
10. A method of three-dimensional ultrasound imaging of a lumen comprising
the steps of:
providing an ultrasound imaging probe comprised of a transducer mounted on
a drive shaft;
providing a rotational drive motor operatively connected to the drive
shaft;
providing a linear translation motor operatively connected to the imaging
probe; and
automatically pulling back the imaging probe by linearly translating the
imaging probe and asynchronously rotating the imaging probe while
activating the transducer and receiving signals from the transducer.
11. The method of claim 10, further comprising the step of providing an
ultrasound transceiver operatively connected to the transducer to activate
the transducer at a constant pulse rate and receive signals from the
transducer.
12. The method of claim 10, further comprising the step of processing the
signals received from the transducer during simultaneous rotation and
linear translation to construct a three-dimensional image of the lumen.
13. The method of claim 12, further comprising the steps of:
slidably mounting the rotational drive motor on a fixed guide rail; and
providing a guide sheath around the imaging probe and fixing the
longitudinal position of the guide sheath relative to the linear
translation module so that the imaging probe translates within the guide
sheath.
14. An automated longitudinal position translator for ultrasonic imaging
probes having a housing and a distally located ultrasound transducer
subassembly, said position translator comprising:
a probe drive module which rotates the ultrasound transducer subassembly of
the imaging probe;
a motor-driven linear translation module to affect motor-driven
longitudinal translation of said probe drive module to longitudinally
shift said ultrasound transducer subassembly between spaced-apart
positions relative to said probe housing; and
a clutch for switching between an automatically-operable condition wherein
said probe drive module is coupled to said motor-driven translation module
to affect said motor-driven longitudinal translation thereof relative to
the probe housing, and a manually-operable condition wherein said probe
drive module is capable of being longitudinally shifted manually relative
to the probe housing.
15. The position translator of claim 14, further comprising at least one
elongate guide rail.
16. The position translator of claim 15, further comprising a second
elongate guide rail, such that the position translator has a pair of
elongate guide rails.
17. The position translator of claim 16, further comprising forward and
rearward transverse support arms connected to and spanning the distance
between said pair of elongate guide rails.
18. The position translator of claim 17, wherein said linear translation
module includes a pair of restraining posts adapted to contact respective
ones of said forward and rearward transverse support arms in interference
fit so as to releasably restrain said probe drive module in said
automatically-operable condition.
19. The position translator of claim 14, wherein said ultrasound transducer
subassembly of said ultrasonic imaging probe includes a flexible rotatable
drive element disposed within a flexible guide catheter sheath.
20. The position translator of claim 19, further comprising:
a longitudinally fixed but rotatable drive coupling capable of being
fixedly attached to the proximal end of said rotatable drive element; and
a longitudinally adjustable coupling which is longitudinally adjustable
with respect to said rotatable drive coupling and which is capable of
being fixedly attached to the proximal end of said guide catheter sheath.
21. The position translator of claim 20, wherein said longitudinally
adjustable coupling includes a barrel-shaped housing having a
longitudinally extending slot.
22. The position translator of claim 21, wherein said housing includes
upper and lower housing sections, and wherein said lower housing section
defines an inner bearing surface for supporting said positioning arm
during movements thereof between advanced and retracted positions.
Description
CROSS-REFERENCE TO RELATED PATENTS AND APPLICATIONS
This application is related to commonly owned U.S. Pat. No. 5,115,814
issuing on May 26, 1992 to James M. Griffith et al, and entitled
"Intravascular Ultrasonic Imaging Probe and Methods of Using Same", which
is the parent of commonly owned U.S. patent application Ser. No.
07/840,134 filed on Feb. 24, 1992 and now abandoned, the entire content of
each being expressly incorporated hereinto by reference.
FIELD OF INVENTION
The present invention generally relates to elongate probe assemblies of
sufficiently miniaturized dimensions so as to be capable of navigating
tortuous paths within a patient's organs and/or vessels. In preferred
forms, the present invention is embodied in automated units which are
connectable to a probe assembly having a distally located ultrasound
transducer subassembly which enables the transducer subassembly to be
positioned accurately by an attending physician and then translated
longitudinally (relative to the axis of the elongate probe assembly)
within the patient under automated control.
BACKGROUND OF THE INVENTION
I. Introductory Background Information
Probe assemblies having therapeutic and/or diagnostic capabilities are
being increasingly utilized by the medical community as an aid to
treatment and/or diagnosis of intravascular and other organ ailments. In
this regard, U.S. Pat. No. 5,115,814 discloses an intravascular probe
assembly with a distally located ultrasonic imaging probe element which is
positionable relative to intravascular sites. Operation of the ultrasonic
element in conjunction with associated electronic components generates
visible images that aid an attending physician in his or her treatment of
a patient's vascular ailments. Thus, a physician may view in real (or
essentially near real) time intravascular images generated by the
ultrasonic imaging probe element to locate and identify intravascular
abnormalities that may be present and thereby prescribe the appropriate
treatment and/or therapy.
The need to position accurately a distally located operative probe element
relative to an intravascular site using any therapeutic and/or diagnostic
probe assembly is important so that the attending physician can
confidently determine the location of any abnormalities within the
patient's intravascular system. Accurate intravascular position
information for the probe assembly will also enable the physician to later
replicate probe positions that may be needed for subsequent therapeutic
and/or diagnostic procedures. For example, to enable the physician to
administer a prescribed treatment regimen over time and/or to later
monitor the effects of earlier therapeutic procedures.
Recently ultrasonic imaging using computer-assisted reconstruction
algorithms has enabled physicians to view a representation of the
patient's interior intravascular structures in two or three dimensions
(i.e., so-called three dimensional or longitudinal view reconstruction).
In this connection, the current image reconstruction algorithms employ
data-averaging techniques which assume that the intravascular structure
between an adjacent pair of data samples will simply be an average of each
such data sample. Thus, the algorithms use graphical "fill in" techniques
to depict a selected section of a patient's vascular system under
investigation. Of course, if data samples are not sufficiently closely
spaced, then lesions and/or other vessel abnormalities may in fact remain
undetected (i.e., since they might lie between a pair of data samples and
thereby be "masked" by the image reconstruction algorithms mentioned
previously).
In practice, it is quite difficult for conventional ultrasonic imaging
probes to obtain sufficiently closely spaced data samples of a section of
a patient's vascular system under investigation since the reconstruction
algorithms currently available depend upon the software's ability to
process precisely longitudinally separated data samples. In this regard,
conventional intravascular imaging systems depend upon manual longitudinal
translation of the distally located ultrasound imaging probe element by an
attending physician. Even with the most skilled physician, it is
practically impossible manually to exercise constant rate longitudinal
translation of the ultrasound imaging probe (which thereby provides for a
precisely known separation distance between adjacent data samples). In
addition, with manual translation, the physician must manipulate the
translation device while observing the conventional two dimensional
sectional images. This division of the physician's attention and
difficulty in providing a sufficiently slow constant translation rate can
result in some diagnostic information being missed. In order to minimize
the risk that diagnostic information is missed, then it is necessary to
devote more time to conducting the actual imaging scan which may be
stressful to the patient.
Thus, what has been needed in this art, is an ultrasound imaging probe
assembly which is capable of being translated longitudinally within a
section of a patient's vascular system at a precise constant rate. Such an
ability would enable a series of corresponding precisely separated data
samples to be obtained thereby minimizing (if not eliminating) distorted
and/or inaccurate reconstructions of the ultrasonically scanned vessel
section (i.e., since a greater number of more closely spaced data samples
could , reliably be obtained). Also, such an assembly could be operated in
a "hands-off" manner which would then allow the physician to devote his
attention entirely to the real time images with the assurance that all
sections of the vessel were displayed. In terms of reconstruction, the
ultrasound imaging probe could be removed immediately and the physician
could interrogate the images or their alternative reconstructions on a
near real time basis. Such a feature is especially important during
coronary diagnostic imaging since minimal time would be needed to obtain
reliable imaging while the blood flow through the vessel is blocked by the
probe assembly. It is therefore towards fulfilling such needs that the
present invention is directed.
II. Information Disclosure Statement
One prior proposal for effecting longitudinal movements of a distally
located operative element associated with an elongate probe assembly is
disclosed in U.S. Pat. No. 4,771,774 issued to John B. Simpson et al on
Sep. 20, 1988 (hereinafter "Simpson et al '774"). The device disclosed in
Simpson et al '774 includes a self-contained motor drive unit for rotating
a distally located cutter element via a flexible drive cable with manual
means to effect relative longitudinal movements of the rotating cutter
element.
More specifically, in Simpson et al '774, the proximal end of a flexible
drive cable is slidably coupled to a hollow extension rotary drive shaft
with a splined shaft. The hollow extension drive shaft is, in turn,
coupled to a motor, whereas the splined shaft cooperates with a manually
operated slide member. Sliding movements of the slide member relative to
the motor drive unit housing translate into direct longitudinal movements
of the flexible drive cable, and hence the distally located cutter
element. In brief, this arrangement does not appear to allow for automated
longitudinal movements of the distally located probe element.
SUMMARY OF THE INVENTION
The longitudinal position translator of the present invention is especially
adapted for use with an intravascular probe assembly of type disclosed in
the above-mentioned U.S. Pat. No. 5,115,814 (incorporated fully by
reference hereinto). That is, the preferred intravascular probe assembly
with which the position translator of the present invention may be used
will include a flexible guide sheath introduced along a tortuous path of a
patient's vascular system, and a rotatable probe element (preferably an
ultrasonic imaging probe) which is operatively introduced into the lumen
of the guide sheath. Of course, the position translator of the present
invention may be modified easily to accommodate less complex one-piece
ultrasonic probe assemblies. Rotational movements supplied by a
patient-external motor are transferred to a distally located transducer
subassembly by means of a flexible torque cable which extends through the
guide sheath.
As is described more completely in U.S. Pat. No. 5,115,814, the interior of
the guide sheath provides a bearing surface against which the probe
element rotates. This beating surface supports the probe element during
its rotation so that virtually no "play" is present--that is, so that the
probe element rotates essentially coaxially relative to the vascular
vessel undergoing therapy and/or investigation. The probe element is also
longitudinally (i.e. axially) movable so that axial-spaced 360.degree.
data sample "slices" of the patient's vascular vessel wall can be imaged.
The automated longitudinal position translator of the present invention
generally includes a probe drive module and a linear translation module.
The probe drive module is most preferably embodied in an elongate
barrel-shaped housing structure having a manual positioning lever capable
of reciprocal movements between advanced and retracted positions. The
lever captures a proximal end of the guide sheath within which a probe
element is disposed. A flexible torque cable connects the transducer
subassembly at the distal end of the probe element to a drive shaft which
is driven, in the preferred embodiment, by a precision rate-controlled
motor located in a separate fixed base unit. Preferably, the housing is
hinged in a "clamshell" fashion to more easily facilitate electrical and
mechanical coupling of the intravascular probe assembly. The lever may be
eliminated when using less complex one-piece ultrasonic probe assemblies
or modified so as to capture the guide catheter or introducer.
The linear translation module supports the probe drive module. In addition,
the linear translation module is coupled operatively to the probe drive
module so as to allow for relative hinged movements thereby and thus
permit the probe drive module to be moved between a manually-operable
condition (whereby the probe drive module is disengaged from the
longitudinal drive subassembly associated with the linear translation
module to thereby allow a physician to exercise manual control over the
longitudinal positioning of the probe element) and an automated condition
(whereby the probe drive module is operatively engaged with the linear
translation module so that automated longitudinal position control over
the probe element can be exercised).
In use, the ultrasound imaging probe will be physically positioned by an
attending physician within a section of a patient's vascular system under
investigation using conventional fluoroscopic positioning techniques.
Thereafter, the proximal portion of the probe and guide sheath assembly
will be coupled to the probe drive module. The probe drive module can then
be employed to either manually or automatically translate the imaging
probe element longitudinally within the section of the patient's vascular
system under investigation during an ultrasonic imaging scan of the same
as may be desired by the attending physician by moving the probe drive
module between its manual and automated conditions, respectively. The
present invention thus allows the distally located probe element to be
rotated, while simultaneously providing the attending physician with the
capability of longitudinally translating the probe element at a constant
automated translation rate to thereby obtain reliable data samples
representative of longitudinally spaced-apart data "slices" of the
patient's vascular section under investigation. These data "slices" may
then be reconstructed using conventional computer-assisted algorithms to
present the entire section of the patient's vascular system under
investigation in a more informative "two-dimensional" longitudinal or
"three-dimensional" image display on a CRT (or other) monitor. The
physician can thus manipulate the image orientation or two-dimensional
sectional plane of the vascular section electronically and thereby achieve
a more informative representation of the condition of the patient's
vascular section under investigation.
In its preferred embodiment, the linear position translator provides for
automated translation of the imaging probe from a distal location to a
proximal location only. Thus, the imaging probe would not be advanced
under automated control into the guide sheath. Such a preferred functional
attribute eliminates the need for sophisticated sensor and control systems
to sense and stop probe advancement should it encounter a "kink" or
non-negotiable sharp bend in the guiding sheath. Furthermore, during probe
withdrawal (i.e., distal to proximal motion), the guide sheath is
supported by the probe and may not "kink". Also, since the probe has
already negotiated all bends during its initial manual distal advancement,
the attending physician is assured that the bends are in fact negotiable
by the probe upon its withdrawal through that same path. Thus, although
the preferred embodiment contemplates automated longitudinal translation
in a proximal direction, it is likewise preferred that the attending
physician advance the probe in a distal direction manually so that the
physician may use his or her experience with the catheters and the tactile
sensations to judge when an obstruction has been encountered.
Further features and advantages of the present invention will become more
clear after careful consideration is given to the following detailed
description of presently preferred exemplary embodiments.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Reference will hereinafter be made to the accompanying drawings wherein
like reference numerals throughout the various FIGURES denote like
structural elements, and wherein;
FIG. 1 is a schematic view of an ultrasonic imaging system that includes an
automated longitudinal position translator according to the present
invention;
FIG. 2 is a top plan view of the probe drive module employed with the
longitudinal position translator according to the present invention
showing the housing thereof in an opened state;
FIG. 3 is a side elevation view, partly in section, of the probe drive
module shown in FIG. 2;
FIGS. 4A and 4B are each side elevation views of the longitudinal position
translator according to the present invention in its automated and manual
conditions, respectively;
FIGS. 5A and 5B are each top plan views of the longitudinal position
translator according to the present invention in its automated and manual
conditions, respectively;
FIGS. 6A and 6B are each front end elevational views of the longitudinal
position translator according to the present invention in its automated
and manual conditions, respectively;
FIG. 7 is a partial side elevational view which is also partly in section
of the longitudinal position translator according to the present
invention; and
FIGS. 8A-8C are top plan views of the longitudinal position translator
according to this invention which schematically depict a preferred mode of
automated operation.
DETAILED DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENTS
A schematic diagram of an exemplary ultrasound imaging system 10 is shown
in accompanying FIG. 1. System 10 generally includes an ultrasound imaging
probe assembly 12 having a guide sheath 14 and a distally located
ultrasound imaging probe element 16 inserted into the lumen of guide
sheath 14, the probe element 16 being depicted in FIG. 1 as being visible
through the guide sheath's transparent wall. The ultrasonic imaging probe
assembly 12 preferably embodies those features more fully described in the
above-identified U.S. Pat. No. 5,115,814.
The overall length of the imaging probe assembly 12 is suitable for the
desired diagnostic and/or therapeutic intravascular procedure. For
example, the overall length of the probe assembly 12 may be shorter for
direct (e.g., arteriotomy) insertions as compared to the length of the
probe assembly 12 needed for percutaneous distal insertions (e.g., via the
femoral artery). A representative length of the imaging probe assembly 12
is therefore shown in the accompanying drawings for clarity of
presentation.
The terminal end of the guide sheath 14 preferably carries a radiopaque
marker band IS formed of gold or other fluoroscopically visible material.
The marker band 18 allows the attending physician to monitor the progress
and position of the guide sheath 14 during intravascular insertions using
standard fluoroscopic imaging techniques.
The proximal end of the imaging probe assembly 12 is received within a
probe drive module 20. In essence, the probe drive module 20 includes a
distally open-ended and longitudinally barrel-shaped housing 22, and a
positioning lever 24 which captures the proximal end of the guide sheath
14. The proximal end of the ultrasound imaging probe element 16 is
mechanically and electrically connected to the probe drive module 20.
Longitudinal reciprocal movements of the positioning lever 24 relative to
the housing 22 will thus in turn effect relative longitudinal
displacements of the distal end of the probe element 16 within the guide
sheath 14 relative to the longitudinal axis of the probe assembly 12.
The probe drive module 20 also includes a drive unit 26 fixedly connected
proximal to the housing 22 and contains the structures which supply
mechanical rotation and electrical signals to the probe element 16. In the
preferred embodiment, mechanical rotation of the probe element 16 is
provided by a separate precision motor 28 associated with a base unit (not
shown) and operatively coupled to the probe drive module 20 via a flexible
drive cable 28a. It is entirely conceivable, however, that the drive unit
26 could be sized so as to accommodate the motor 28.
The drive unit 26 is most preferably configured so that the attending
physician may comfortable grasp its exterior with one hand while the probe
drive module 20 is in its manual condition. The drive unit 26 thus forms a
handle which allows the physician to manually manipulate the relative
position between the housing 22 and the positioning lever 24 thereby
responsively permitting manual longitudinal movements to be imparted to
the probe element 16. A thumb/finger switch 30 may thus be manually
depressed to allow the physician to selectively operate the drive unit 26
and thereby rotate the ultrasonic imaging probe element 16 when it is
desired to conduct an ultrasonic imaging scan. Electrical connection
between the switch 30 and the control console 46 is made via I/O cabling
41.
During rotation, electrical communication is established between the
transducer subassembly in the distal end of the ultrasonic imaging probe
element 16 and the ultrasound transceiver 40 via patient-internal
electrical coaxial cabling (not shown) within the probe element 16, drive
unit 26 and electrical patient-external I/O cabling 41. The ultrasound
transceiver 40 produces a pulse signal (of desired magnitude and shape)
which is applied via the electrical cabling 41 to an electroacoustic
transducer associated with the distal end of the probe element 16. The
transceiver 40 also performs conventional signal processing operations
(e.g., amplification, noise reduction and the like) on electrical signals
generated by the electromechanical excitation of the transducer within the
probe element 16 (i.e., signals generated by the transducer in response to
receiving acoustic echo waves).
These signals are further processed digitally via known display algorithms
(e.g., conventional PPI (radar) algorithms) and are then supplied as input
to a CRT monitor 42 (or any other equivalent display device) so as to
generate an ultrasound image 44 of desired format representative of the
vascular structures reflecting ultrasonic energy toward the transducer
within the distal end of the probe element 16. A control console 46 may be
employed by the attending physician so as to select the desired
operational parameters of the ultrasound transceiver 40 and/or the display
format of the image 44 on the CRT 42, for example.
The probe drive module 20 is operatively coupled to and supported by the
linear translation module 48 so as to allow for reciprocal rectilinear
movements of the housing 22/drive unit 26 relative to both the linear
translation module 48 and the positioning arm 24 which collectively remain
in a fixed position as will be described in greater detail below. As will
also be described in greater detail below, the probe drive module 20 is
mounted for hinged movements relative to the linear translation module 48
between a manually-operable condition (whereby the probe drive module 20
is operatively disengaged from the motor driven translator associated with
the linear translation module 48) and a automatically-operable condition
(whereby, the probe drive module 20 is operatively engaged with the motor
driven translator associated with the linear translation module 48).
The linear translation module 48 includes a proximal housing 48a which
contains appropriate speed-reducers, drive shafts and associated couplings
to be described below in connection with FIG. 7. Suffice it to say here,
however, that driven power is provided to the structures internally of
housing 48a by a separated precision motor 50 associated with a system
base unit (not shown) which is coupled operatively to the structures
internally of housing 48a via a flexible drive shaft 50a. Again, it is
entirely conceivable that the housing 48a of the linear translation module
48 could be sized and configured so as to accommodate the motor 50.
Automated operation of the motor 50 (and hence the linear translation
module 48) may be accomplished through the selection of appropriate
operation parameters by the attending physician via control console 46.
Operation of both the linear translation module 48 and the probe drive
module 20 may be initiated by depressing the foot-switch 27.
The exemplary probe drive module 20 which is employed in the present
invention is perhaps more clearly depicted in accompanying FIGS. 2 and 3.
As is seen, the housing 22 is collectively formed of a pair of elongate
lower and upper housing sections 51, 52, respectively, which are coupled
to one another along adjacent longitudinal edges in a clamshell-hinged
arrangement via hinge pin 54.
It will be noticed with particular reference to FIG. 2 that the proximal
and distal ends 54a, 54b of pin 54 are rigidly fixed to the proximal and
distal ends 51a, 51b of housing section 51, respectively, while the
housing section 52 is pivotally coupled to the pin 54 (and hence the
housing section 51) by means of proximal and distal and intermediate pivot
sleeves 56a, 56b and 56c, respectively. The housing sections 51, 52 are
maintained in their closed state (i.e., as shown in FIGS. 4A through 5B)
by means of a spring-loaded detent 57a (see FIG. 2) which may be moved
into and out of an aperture (not shown) formed in the housing section 51
via operating lever 57b.
The positioning lever 24 is oriented transversely relative to the elongate
axis of housing 22. In this regard, the lever 24 includes a sleeve end 24a
which is coupled to the pivot pin 54 to allow reciprocal longitudinal and
pivotal movements of the lever 24 to occur relative to the longitudinal
axis of pin 54. The opposite end 24b of lever 24 extends radially
outwardly from the housing 22.
The housing 22 defines an elongate slot 58 when the housing sections 51, 52
are in a closed state (i.e., as depicted in FIG. 1). The slot 58 allows
the positioning lever 24 to be manually moved along the longitudinal axis
of pin 54 during use (i.e., when the housing sections 51, 52 are in a
closed state) between retracted and extended positions (shown respectively
by phantom line representations 24' and 24" in FIG. 2). The retracted
position 24' of lever 24 is established by a distal face of a pivot sleeve
56c integral with the housing section 52 and pivotally coupled to pin 54
in a manner similar to pivot sleeves 56a and 56b. On the other hand, the
extended position 24" of lever 24 is established by a proximal face of
pivot sleeve 56b.
The lever 24 is supported by a concave inner surface 59 formed in the
housing section 51 when the housing sections 51 and 52 are in a closed
state. The inner surface 59 provides a bearing surface against which the
lever 24 slides during the latter's movement between its retracted and
extended positions 24' and 24", respectively.
A scale 60 (see FIGS. 4A and 5A) preferably is provided on the housing 22.
A pointer 24c associated with the lever 24 may be aligned with the scale
60 to provide an attending physician with information regarding the
position of probe element 16 relative to its most distal position within
the guide sheath 14. That is, longitudinal movement of lever 24 an
incremental distance (as measured by pointer 24c and the scale 60) will
effect movement of the probe element 16 relative to its most distal
position within the guide sheath's distal end by that same incremental
dimension.
Accompanying FIG. 2 also more clearly shows the cooperative engagement
between positioning lever 24 and the proximal end of guide sheath 14. In
this regard, it will be noted that the proximal end of guide sheath 14
includes a side-arm port 70 which extends generally transverse to the
longitudinal axis of guide sheath 14. Side-arm port 70 includes a
conventional Leur-type locking cap 72 that is coupled coaxially to a
similar locking cap 74 associated with the proximal end of guide sheath
14. Side-arm port 70 is thus in fluid-communication with the lumen of
guide sheath 14 so that saline solution, for example, may be introduced
via side-arm tubing 70a.
A shaft extension 75 of probe element 16 and electrical cabling coaxially
carried thereby are mechanically and electrically coupled to the output
shaft 77 of the probe drive module 20 via coaxial cable couplings 75a and
75b. It will be appreciated that coaxial cabling within the flexible
torque cable portion of probe element 16 (not shown) will rotate with it
as a unit during operation, but that the electrical I/O signals will be
transferred to transceiver 40 by means of couplings 75a and 75b. The
manner in which the separate electrical I/O path (represented by cable
41--see FIG. 1) and mechanical input path (represented by the flexible
drive shaft 28a--see FIG. 1) are combined into a common
electrical/mechanical output path (represented by output shaft 77) will be
explained in greater detail with reference to FIG. 3.
The shaft extension 75 is preferably fabricated from a length of
conventional stainless steel hypodermic tube and is rigidly coupled at its
distal end to a flexible torque cable (not shown). As mentioned briefly
above, the torque cable extends the length of the guide sheath 14 and is
connected at its distal end to a transducer subassembly in the distal end
of the probe element 16. The torque cable thereby transfers the rotational
motion imparted via the motor to shaft extension 75 of the probe element
16 causing the transducer subassembly to similarly rotate within the lumen
of the guide sheath 14 near the guide sheath's distal end, as well as to
be longitudinally shifted within guide sheath 14 via manipulation of the
relative position of the arm 24.
The shaft extension 75 extends through an end cap 76 which is coupled
coaxially to locking caps 72 and 94. End cap 76 houses a synthetic resin
bearing element (not shown) which serves as a proximal rotational bearing
for the shaft 75, and also serves to seal the proximal end of guide sheath
114 against fluid (e.g., saline liquid) leakage.
Lever 24 defines a pair of mutually transverse concave cradle surfaces 80
and 82. The longitudinal dimension of cradle surface 80 is oriented
parallel to the longitudinal dimension of housing 22, whereas cradle
surface 82 (which is joined at one of its ends to the cradle surface 80)
is oriented transverse to the longitudinal dimension of housing 22 (i.e.,
since it is traverse to cradle surface 80).
Cradle surface 80 is sized and configured so as to accommodate an exterior
surface portion of coaxially locked caps 72, 74 and 76. Cradle surface 82,
on the other hand, is sized and configured to accept side-arm port 70 and
side-arm tubing 70a extending therefrom. An axially extending inner
concave surface 84 is defined in housing section 52 and, like cradle
surface 82, is sized and configured so as to accept an exterior portion of
locking caps 72, 74 and 76.
When housing sections 51 and 52 are in a closed state, caps 72, 74 and 76
will be enveloped by housing 22. More specifically, inner concave surface
84 will positionally restrain caps 72, 74 and 76 within cradle surface 80
when housing sections 51 and 52 are closed. Since side-arm port 70 will
likewise be positionally restrained within cradle surface 82 when housing
sections 51, 52 are closed, caps 72, 74 and 76 will be moved
longitudinally as a unit with position lever 24. That is, longitudinal
movements of lever arm 24 between its retracted and extended positions
will cause the proximal end of guide sheath 14 (i.e., coaxially mounted
caps 72, 74 and 76) to be longitudinally moved relative to the
longitudinally stationary (but axially rotatable) shaft extension 75. In
such a manner, the proximal end of guide sheath 14 will be moved closer to
and farther from the open distal end of housing 22.
As can be seen in FIG. 3, the interior of the drive unit 26 is hollow to
house electrical/mechanical coupling assembly 85. Electrical/mechanical
coupling 85 combines an electrical input path--represented by coaxial I/O
cable 41 which establishes electrical communication with transceiver
40--and a mechanical input path--represented by flexible drive shaft 28a
associated with motor 28 (see FIG. 1) into a common coaxial output shaft
77.
Output shaft 77 is rotatably held within bearing block 86 and includes a
rearwardly extending rotatable tail portion carrying a number of
electrical slip-rings 86a. Electrical communication between the slip-rings
86a and, coupling 75b is established by a length of coaxial cable (not
shown) housed within the output shaft 77. Stationary brushes 88a in
sliding electrical contact with respective ones of the slip-rings 86a are
associated with a brush block 88. Lead wires 88b are, in turn, coupled
electrically at one end to brush block 88 (and hence to coaxial connector
75a via brushes 88a and slip-rings 86a), and at the other end to coaxial
I/O cable 41 via a ferrite coil transformer (not shown). Slip-rings 86a,
brush 88a, brushes block 88, lead wires 88b, and ferrite core transformer
(not shown) are housed within a common electrically shielded enclosure 90.
The mechanical input path generally represented by flexible drive shaft 28a
is coupled operatively to one end of a rigid rotatable drive shaft 92
carrying a drive gear 94 at its other end. Drive gear 94 is, in turn,
meshed with a gear 96 carried by output shaft 77. Upon rotation of drive
shaft 92, meshed gears 94, 96 will cause shaft 77 to responsively rotate.
Preferably, gears 94 and 96 are in a 1:1 ratio, but other gear sizes (and
hence ratios) may be provided if desired.
The probe drive unit 20 is mounted for reciprocal rectilinear movements to
the linear translation module 48 as is shown in accompanying FIGS. 4A
through 6B. In this regard, the linear translation module includes a base
plate 100 which supports the housing 48a and its internal structures (to
be described below with reference to FIG. 7). The probe drive module 20
itself includes a longitudinally spaced-apart pair of support flanges 102,
104, each of which is slidably mounted onto a pair of parallel guide rails
106, 108.
The proximal end of guide rail 106 is pivotally connected to the housing
48a while its distal terminal end is pivotally connected to an upright
support block 106a. A forward and rearward pair of transverse support arms
110, 112 each having one end rigidly coupled to guide rail 106 and an
opposite end rigidly coupled to the guide rail 108. Thus, the support arms
110, 112 are capable of pivoting between a lowered position (e.g., as
shown in FIGS. 4A, 5A and 6A) and a raised position (e.g., as shown in
FIGS. 4B, 5B and 6B) by virtue of the pivotal guide rail 106 so as to, in
turn, pivotally move the probe drive module 20 between its
automatically-operable condition and its manually-operable condition,
respectively, due to its attachment to the guide rails 106, 108 via
support flanges 102, 104.
The ends of each transverse support arm 110, 112 between which the guide
rail 108 is fixed are removably captured by upright restraining posts 114,
116, respectively. As is perhaps more clearly shown in FIGS. 6A and 6B,
the restraining posts 114, 116 (only restraining post 114 being visible in
FIGS. 6A and 6B) are rigidly supported by the base plate 100 and include
an inwardly projecting lip 114a, 116a which provide an interference fit
with the terminal ends of support arms 110, 112, respectively. In this
connection, it is preferred that the restraining posts 114, 116 be formed
of a relatively stiff, but resilient plastics material (e.g., nylon,
polyacetal or the like) so that when the probe drive unit is moved between
its automatically-operable and manually-operable conditions, the posts
114, 116 are capable of yielding somewhat to allow such movement.
The positioning arm 24 of the probe drive unit 20 is fixedly tied to the
forward transverse support arm 110 by an upright connector 120a on a
longitudinal connector 120b. In this regard, the upper end of upright
connector 120a extends through a longitudinal slot on the side of the
housing 22 opposite slot 58 and positionally captures the ends of the
positioning arm 24 around pin 54. The lower end of the upright connector
120a is connected to the distal end of the horizontally disposed
longitudinal connector 120b. The proximal end of longitudinal connector
120b is, in turn, rigidly fixed to the transverse support arm 110 by any
suitable means (e.g., screws). It will be understood, therefore, that the
position of the positioning arm 24 (and hence the guide sheath 14) remains
fixed relative to the base 100 of the linear translation module 48 during
longitudinal movements of the probe drive module 20 along the guide rails
106 and 108. Thus, the relative position of the patient-internal
transducer subassembly at the distal end of the probe element 16 will
correspondingly shift the same distance as the probe drive module 20
relative to the patient internal distal end of the guide sheath 14.
Automated longitudinal shifting of the probe drive module 20 (and hence the
ultrasonic transducer at the distal end of the robe element 16) is
permitted by the coaction between a longitudinally extending drive screw
120 and a threaded collar portion 122 (see FIGS. 4B and 7) associated with
the support flange 102 of the probe drive module 20. The distal and
proximal ends of the drive screw 120 are rotatably supported by an upright
distal bearing block 124 and an upright proximal bearing block 126 (see
FIG. 7), respectively.
As can be seen in FIGS. 4B, 5B, 6B and 7, the threaded collar portion 122
is disengaged from the threads of drive screw 120 when the probe drive
module 20 is in its manually-operable condition. As a result, the
attending physician may simply manually shift the probe drive module 20
longitudinally along the guide rails 106, 108. When the probe drive module
20 is pivoted into its automatically-operable condition as shown in FIGS.
4A, 5A and 6A, the threads associated with the threaded collar portion 122
will be mateably engaged with the threads of the drive screw 120. As a
result, rotation of the drive screw 120 about its longitudinal axis will
translate into longitudinal displacement of the probe drive module 20. The
threads of the drive screw 120 and the threaded collar portion 122 as well
as the rotation direction of the drive screw 120 are most preferably
selected so as to effect longitudinal shifting of the probe drive module
from the distal end of the drive screw towards the proximal end
thereof--i.e., a distal to proximal displacement. However, these
parameters could be changed so as to effect a reverse (proximal to distal)
displacement of the probe drive unit, if necessary or desired.
The drive screw 120 is coupled operatively to the flexible drive shaft 50a
(and hence to the driven output of motor 50) by the structures contained
within housing 48a. In this regard, the proximal end of the drive screw is
coupled to the output shaft of a speed reducer 128 via a shaft coupling
130. The input to the speed reducer 128 is, in turn, coupled to the
flexible drive shaft 50a from a rigid shaft extension member 132 and its
associated shaft couplings 132a and 132b. The speed reducer 128 is of a
conventional variety which provides a predetermined reduced rotational
speed output based on the rotational speed input. Preferably, the motor
50, speed reducer 128 and drive screw 120 are designed so as to effect
longitudinal translation of the probe drive unit 20 at a rate of between
about 0.25 to 1.0 mm/sec. Of course, other longitudinal translation rates
may be provided by varying the parameters of the motor 50, speed reducer
128 and/or drive screw 120.
In use, the attending physician will preposition the guide sheath 14 and
imaging probe element 16 associated with the ultrasound imaging probe
assembly 12 within the vessel of the patient to be examined using standard
fluoroscopic techniques and/or the techniques disclosed in the
above-mentioned U.S. Pat. No. 5,115,814. Once the guide sheath 14/imaging
probe element 16 have been prepositioned in a region of the patient's
vessel which the physician desires to observe, the proximal end of the
probe assembly 12 will be coupled to the probe drive module 20 in the
manner described above. Thereafter, the physician may conduct an
ultrasound scan of the patient's vessel by operating switch 30 to cause
high-speed rotation of the transducer subassembly on the distal end of the
probe element 16 within the guide sheath 14. Data samples associated with
different transverse sections of patient's vessel may then be obtained by
the physician manually shifting the probe drive module 20 along the guide
rails 106, 108 in the manner described above.
Alternatively, the physician may elect to pivot the probe drive module 20
into its automatically-operable condition and then select automated
operation of the same via the control console 46 and foot-switch 27. In
such a situation, the probe drive module (and hence the transducer
subassembly at the distal end of the probe element 16) will be shifted
longitudinally at a constant rate simultaneously with high-speed rotation
of the transducer subassembly. In this manner, data samples representing
longitudinally spaced-apart 360" "slices" of the patient's interior vessel
walls will be accumulated which can then be reconstructed using known
algorithms and displayed in "two-dimensional" or "three-dimensional"
formats on the monitor 42.
Accompanying FIGS. 8A-8C schematically depict the longitudinal translator
according to this invention being operated in an automated manner. In this
connection, and as was noted briefly above, the probe drive module 20 is
most preferably translated in a distal to proximal direction by means of
the linear translation module 48 (i.e., in the direction of arrows 140 in
FIGS. 8A and 8B). In FIG. 8A, the probe drive module is shown in a
position at the beginning of an automated ultrasonic imaging scan, it
being noted that the pointer 24c.associated with the positioning arm 24
registers with the zero marking on the scale 60. The physician will then
initiate automated ultrasonic scanning via the foot-switch 27 which causes
the probe drive unit 20 to be displaced proximally (arrow 140) at a
constant rate as shown in FIG. 8B. This proximal displacement of the probe
drive module 20 will, in turn, cause the transducer subassembly on the
distal end of the probe element 16 to be longitudinally displaced
proximally (i.e., pulled back away from) the distal-most end of the guide
sheath 14.
The ultrasonic imaging scan is automatically terminated (e.g., by use of
suitable limit switches and/or position transducers) when the probe drive
unit reaches the its most proximal position as shown in FIG. 8C. In this
connection, the present invention most preferably is provided with a limit
switch (not shown) enclosed within a limit switch housing 29 (see FIGS. 4a
and 5B) which is mechanically actuated when support flange 102 contacts
support arm 112 (i.e., when the probe drive module 20 is in its most
proximal position). The limit switch in housing 29 communicates
electrically with the control console 46 via cabling 41.
Virtually any suitable equivalent position-sensing devices could be
employed in place of the limit switch. For example, the housing 29 could
be sized and configured to accommodate an absolute position transducer so
as to communicate absolute position to the control console 46. The
information provided by such an absolute position transducer could be
employed in conjunction with modified reconstruction algorithms for image
reconstruction, even during manual operation of the probe drive module 20.
Upon the probe drive module 20 reaching its most proximal position the
pointer 24c associated with the positioning arm 24 registers with the
marking "10" on the scale 60 of housing 22. Of course, the ultrasonic
imaging scan need-not necessarily be conducted over the entire range of
0-10 marked on the scale 60 and thus could be terminated at any time by
the physician simply releasing the foot-switch 27 or by simply pivoting
the probe drive module 20 into its manually-operable condition.
Those skilled in this art will recognize that a number of equivalent
mechanical and/or electrical means could be employed. For example, locking
slides, latches and quarter-turn screws could be used to allow engagement
and disengagement of the probe drive module with the linear translation
module. A flexible drive shaft connects the linear translation module to a
rate-controlled motor which controls the automatic linear translation
rate. The motor is most preferably located in a separate fixed base unit,
but could be provided as in an integral part of the linear translation
module, if desired.
Furthermore, various translation rates associated with the motor may be
selected for various purposes. For example, slow rates give ample time for
the physician to examine the real-time images in cases where time is not a
limiting factor. The rate upper limit is governed by the probe rotation
rate and the effective thickness of the imaging data slices generated by
the probe, such that there is no (or an acceptable) gap between successive
imaging data slices. This would prevent missing discernible features
during vascular imaging with automatic translation. The effective
thickness is governed by the ultrasonic beam characteristics of the probe.
For some applications, the translation may be discontinuous (i.e., gated
to an electrocardiogram) for use with modified algorithms or programmed to
translate a fixed distance discontinuously.
Thus, while the invention has been described in connection with what is
presently considered to be the most practical and preferred embodiment, it
is to be understood that the invention is not to be limited to the
disclosed embodiment, but on the contrary, is intended to cover various
modifications and equivalent arrangements included within the spirit and
scope of the appended claims.
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